Conventionally, a manual valve is installed to a discharge device for a tank of a fluidic device. A conventional manual valve may be installed to a tank by, for example, screwing into a discharge hole of a discharge device installed to a tank. In such a configuration, the manual valve may be unscrewed to drain fluid accumulated in the tank or to vent the tank to enable filling the tank. When the manual valve is unscrewed, the manual valve may be easily detached from the tank. Consequently, it is concerned that the detached manual valve may be lost.